The present invention relates to a spinal-rod connecting apparatus for connecting and supporting bone screws implanted in vertebrae and rods installed in parallel to the vertebrae.
An operation is performed that holds the spine in a desirable position by implanting a required number of bone screws in vertebrae and connecting them to rods. Each of the bone screws has a connecting portion through which the rod is inserted and screwed. Such connecting portions are roughly divided into those shaped like holes formed in what are referred to as xe2x80x9cclosed screws,xe2x80x9d into which rods are inserted in an axial direction, and those shaped like grooves formed in what are referred to as xe2x80x9copen screwsxe2x80x9d for receiving rods therein. However, it may be impossible or difficult to place a rod directly at the corresponding bone screw, that is, at the screw-connecting portion, depending on the site at which the rod is attached. In such cases, it is contemplated that an auxiliary part having a rod may be used. However, in accordance with the object of the auxiliary part, the physician must bend or cut this part in the operating room prior to operation. This is impractical.
The present invention is provided in view of the above points, and it is an object thereof to avoid requiring the physicians to machine, during operation, a connecting apparatus in the operating room, and to allow them to fix rods and bone screws together easily and accurately through the appropriate combination of connectors. It is another object of the present invention to provide a connector that can be preferably used for a spinal-rod connecting apparatus.
These and other objects are attained by a spinal-rod connecting apparatus of the present invention using multiple connectors, each comprising a through-hole through which a rod can be inserted, a short rod having the same diameter as the above rod, with the short rod being directed in a direction substantially orthogonal to an axial direction of the through-hole, and having a length required for the short rod to be inserted and screwed into the through-hole, and an internal thread portion that allows an external thread member to be screwed therein, with the external thread member locking the rod or short rod inserted into the through-hole, wherein a first connector can be set on the rod by inserting the rod into the through-hole therein, the short rod of a second connector can be arranged in a rod-attaching portion of a bone screw, and the short rod of the first connector can be inserted into the through-hole in the second connector.
The spinal-rod connecting apparatus according to the present invention uses connectors each comprising a through-hole through which a rod can be inserted, a short rod having the same diameter as the above rod, with the short rod being directed in a direction substantially orthogonal to an axial direction of the through-hole and having a length required for the short rod to be inserted and screwed into the through-hole, and an internal thread portion that allows an external thread member to be screwed therein, with the external thread member locking the rod or short rod inserted into the through-hole. In addition to the rod and short rod, a transverse rod that links parallel rods together can be inserted into the through-hole. The spinal-rod connecting apparatus according to the present invention connects and supports bone screws implanted in vertebrae, and rods installed in parallel to the vertebrae. The bone screw includes a screw or is a part called an xe2x80x9cimplantxe2x80x9d having a connecting portion into which the rod is inserted and screwed. It does not matter whether the connection portion is of a closed type (hole) or an open type (groove).
The spinal-rod connecting apparatus according to the present invention uses multiple connectors. The connector desirably comprises a through-hole through which a rod can be inserted, a short rod having the same diameter as the above rod, with the short rod being directed in a direction substantially orthogonal to an axial direction of the through-hole, and an internal thread portion that allows an external thread member to be screwed therein, with the external thread member locking the rod or short rod inserted into the through-hole. That is, the short rod and the rod are adapted so as to be freely inserted and screwed into the through-hole in the connector. The short rod is of a length required for it to be inserted and screwed into a through-hole in another connector. Thus, the short rod need not be as long as the long rods found in conventional auxiliary parts.
The through-hole and short rod provided in the connector have an orthogonal relationship, as this arrangement allows the connector to be easily positioned orthogonal to or in parallel to the vertebrae. Further, the spinal-rod connecting apparatus consists of at least two connectors. These connectors may be of the same shape, minimizing the time and costs required for manufacturing the apparatus.
With the multiple connectors, a first connector is set on a rod by inserting the rod into the through-hole therein, the short rod of a second connector is arranged in a rod-attaching portion of a bone screw, and the short rod of the first connector is inserted into the through-hole in the second connector. When the multiple connectors are thus combined, the inclination or the like of the connectors can be corrected by aligning them with the bone screws implanted in the vertebrae, while keeping them parallel with the rods installed in parallel to the vertebrae. That is, the present invention has the advantage of being capable of three-dimensionally modifying the direction in which the bone screws are inserted into the rods when the rods and bone screws are connected.